user_activity: Added tools for the benchmark profile collection.

The scripts run the Telemetry benchmarks, collects their perf profiles, use
local_cwp to do the profile symbolization and collect the hot
functions and callchains with pprof.

BUG=None
TEST=None

Change-Id: I2170e53d95924f1a3ba134bd62b1eead9e7a3077
Reviewed-on: https://chrome-internal-review.googlesource.com/288517


Reviewed-by: Luis Lozano <llozano@chromium.org>
Reviewed-by: Evelina Dumitrescu <evelinad@google.com>
Commit-Queue: Evelina Dumitrescu <evelinad@google.com>
Tested-by: Evelina Dumitrescu <evelinad@google.com>
Reviewed-on: https://chromium-review.googlesource.com/435923


Commit-Ready: Luis Lozano <llozano@chromium.org>
Tested-by: Luis Lozano <llozano@chromium.org>